Filter housing assembly

ABSTRACT

A filter housing assembly having a gas-tight seal and a method of replacing a filter are generally provided. In one embodiment, the filter housing assembly includes a housing having an opening adapted to receive a filter and an inlet. A seal member is coupled to the housing and is moveable between a first position and at least a second position, the second position sealing the inlet. The filter housing assembly may be configured to retain a roomside replaceable filter or have a filter permanently adhered within the opening.

BACKGROUND OF THE DISCLOSURE

1. Field of the Invention

The embodiments of the present invention relate generally to a filterhousing assembly.

2. Background of the Invention

Cleanrooms are utilized in many industries for contamination control andto improve product yields. A plurality of filters, typically mounted inthe ceiling of the cleanroom, are configured to remove particulate fromair entering the cleanroom at a predetermined efficiency selected basedupon the cleanliness requirements of the activities performed in thecleanroom. As particulates load the filtration media disposed in thefilter, the airflow through the filter decreases as the pressure dropacross the filter increases. Once the filter reaches a critical pressuredrop, the filter is typically replaced.

On other applications, replacement of filters is scheduled based on timeor processes performed within the cleanroom. For example, in manypharmaceutical and biotech cleanrooms, periodic replacement of filtersis required to meet regulatory or owner specifications. To facilitateefficient replacement of the filter, a hood (housing) is typicallymounted in the cleanroom ceiling in which the filter may be readilyremoved and replaced.

Ducted supply hoods with roomside replaceable filters are commonly usedin pharmaceutical applications for cleaning supply air to cleanroommanufacturing and process areas, as well as to laboratory areas. Most ofthese hoods are supplied with adjustable dampers that allow customers toregulate the airflow without having to remove the filter from the hood.The most common types of dampers are guillotine, opposed blade andbutterfly types. When completely closed, these dampers essentially stopthe flow of air to the hood. In many cases, the leakage through a closeddamper is negligible in terms of flow rate, but is significant whenconsidered in the terms of contamination of a cleanroom.

Because these types of dampers do not provide a seal (i.e., are notleak-free or bubble-tight), they are inadequate when it comes todecontamination processes that require complete isolation of thecleanroom. For example, during routine testing and validation of filtersinstalled in a pharmaceutical facility, one or more filters may be founddamaged, leaking and/or requiring replacement. When a technician removesthat filter from the hood, the “seal” between the cleanroom and thecontaminated plenum and supply ducts upstream of the removed filter isbroken. When the new filter is installed, the “seal” between those twoareas is restored, but the cleanroom has already been contaminated byair and particulate entering the cleanroom from the contaminated area ofthe plenum and supply ducts. Thus, the facility owner must perform adecontamination process of the entire room before resuming cleanroomoperations. This is a very time-consuming and costly process.

Therefore, there is a need for a filter housing assembly having improvedsealing capabilities.

SUMMARY OF THE INVENTION

A filter housing assembly having a gas-tight seal is provided. In oneembodiment, the filter housing assembly includes a housing having anopening adapted to receive a filter. An inlet is formed through thehousing. A seal member is coupled to the housing and is moveable betweena first position and at least a second position, the second positionsealing the inlet.

In alternate embodiments, the filter housing assembly may be configuredto retain a roomside replaceable filter or a filter permanently adheredto the housing. The filter housing assembly may be utilized to supplyand/or exhaust air from a work space, such as a cleanroom. In variousembodiments, the seal member may be configured as a butterfly damper orguillotine damper, among others.

In another aspect of the invention, a method for replacing an air filteris provided. In one embodiment, the method includes the steps of sealingan inlet to a filter housing, retaining a replaceable air filter,removing the air filter, replacing the air filter with a replacement,installing a replacement air filter and opening the seal to allow airflow through the filter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the invention, briefly summarizedabove, may be had by reference to the embodiments thereof that areillustrated in the appended drawings. It is to be noted, however, thatthe appended drawings illustrate only typical embodiments of thisinvention and, therefore, are not to be considered limiting of itsscope, for the invention may admit to other equally effectiveembodiments.

FIG. 1 depicts a simplified, partial sectional view of one embodiment ofa filter module having a damper assembly;

FIG. 2 is an alternative embodiment of a sealing section of a filterhousing;

FIG. 3 is a partial sectional view of one embodiment of a damperassembly coupled to a housing assembly;

FIG. 4A-E are various embodiments of a sealing element disposed betweena housing assembly and a seal member;

FIG. 5 is partial sectional view of the housing of FIG. 3;

FIG. 6 is a partial sectional view of the damper assembly of FIG. 3 inan open position;

FIG. 7 depicts an alternative embodiment of a seal member and anadjustment mechanism;

FIG. 8 depicts a sectional view of one embodiment of a butterfly damper;

FIG. 9 depicts a sectional view of one embodiment of a guillotinedamper; and

FIG. 10 depicts a sectional view of one embodiment of a diffuser havinga damper assembly.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

FIG. 1 depicts a sectional view of one embodiment of a filter module 100disposed in a ceiling 102 of a cleanroom 104. The filter module 100includes a damper assembly 122 configured to selectively prevent flowthrough the filter module 100 with a bubble-tight seal. Typically,additional filter modules 100 (not shown) are utilized in predeterminedpositions within the cleanroom 104 to provide predetermined levels ofcleanliness and ventilation. The scale of FIG. 1 has been altered toallow details of the module 100 to be clearly shown in a single view.

The filter module 100 generally includes filter housing assembly 106that retains a removable filter 108. The filter housing assembly 106includes a filter housing 180 and a collar 116. The collar 116 may be anintegral part of the housing 180 or separately coupled thereto, andfacilitates coupling the filter housing assembly 106 to a duct 118 thatsupplies air from an air handler 120. The air handler 120 supplies airto the filter module 100. The air handler 120 includes one or moreblowers or fans (not shown) and may additionally include pre-filtrationelements such as ASHRAE or HEPA filters. It is also contemplated thatthe collar 116 may be coupled to an air return to exhaust the roomthroughout the filter 108.

The housing 180 has a plurality of sidewalls 110 and a backplate 112that define an interior volume 114. It is contemplated that cylindricalhousings may utilize a single sidewall 110. The sidewalls 110 andbackplate 112 may be fabricated from a single element of materials, ormay comprise separate components, sealingly coupled together.

The sidewalls 110 and backplate 112 of the housing assembly 106 aregenerally fabricated from metals, such as aluminum or stainless steel,or other materials such as plastic, or glass reinforced plastic, amongothers. The sidewalls 110 are generally configured in a polygonal form,typically square or rectangular. The sidewalls 110 are sealingly coupledtogether at their intersections, for example, by welding, riveting,soldering, adhering, bonding, caulking and the like. The backplate 112is generally coupled to the sidewalls 110 in a similar fashion to makethe housing assembly 106 leak-tight.

The back plate 112 includes an inlet 182 formed therethrough. The inlet182 is circumscribed by the collar 116 and facilitates airflow into theinterior volume 114 of the housing assembly 106. The collar 116 istypically cylindrical, but may alternatively be square, rectangular orhave another shape. An optional lip 184 may extend into the interiorvolume 114 from the backplate 112 and circumscribes the inlet 182. Thelip 184 is sealingly coupled to the backplate 112, for example, bywelding or caulking. The lip 184 may be sealed to the backplate 112 byother methods. The lip 184 may alternatively be drawn, spun or otherwiseformed from the backplate 112. In another embodiment, the lip 184 may bepart of the collar 116. The lip 184 may be utilized to enhance thesealing attributes of the damper assembly 122 as discussed furtherbelow.

Each sidewall 110 includes a first end 124 coupled to the backplate 112and a second end 126 that interfaces with the cleanroom ceiling 102. Thefirst end 124 of the sidewall 110 and/or backplate 112 generallyincludes a mounting pad or tab 146 that facilitates coupling the housing106 to a supporting structure (not shown) above the cleanroom 104. Thesecond end 126 defines an opening that accepts the filter 108 into thehousing assembly 106.

The sidewalls 110 have a double wall that includes an outer section 128disposed against at least a portion of an inner section 130. In theembodiment depicted in FIG. 1, the outer section 128 is disposed betweenthe first end 124 and the second end 126 while the inner section 130extends from the second end 126 along a portion of the outer section 128to a sealing section 132. The outer and inner sections 128, 130 aresealingly joined at the second end 126, and in one embodiment, arefabricated from a continuous piece or sheet of material where the outersection 128 is folded at the second end 126 and transitions into theinner section 130.

In one embodiment, the sealing section 132 includes a knife edge 134that is coupled to the inner section 130 by a flange 136. Typically, theknife edge 134 and flange 136 are fabricated from a single piece ofmaterial, and may also be fabricated with the inner section 130 of thesidewall 110 as a continuous piece of material. The knife edge 134 isorientated substantially parallel to the sidewalls 110 and is configuredto interface with a sealing element 138 disposed at one end the filter108 to create an air-tight seal between the filter housing assembly 106and the filter 108. Thus, the sealing section 132 separates the interiorvolume 114 of the housing assembly 106 into a plenum 148 upstream of thefilter 108 and a downstream or roomside. In other words, the filter 108interfacing with the sealing section 132 separates the unfiltered airupstream of the filter 108 with the clean, filtered air, downstream ofthe filter 108 that enters the cleanroom 104.

In the embodiment depicted in FIG. 1, the sealing element 138 is asilicon or polyurethane gel disposed in a trough 140 formed in a frame142 of the filter 108. The knife edge 134 penetrates the gel to createan air seal between the filter 108 and housing assembly 106. Filterperformance (i.e., efficiency, pressure drop) is generally selectedbased on filtering and resistance criteria needed for a particularapplication to be performed in the cleanroom 104. Filters manufacturedfor this use are commercially available, e.g., from CAMFIL FARR, INC.located in Riverdale, N.J.

FIG. 2 depicts another embodiment of a housing 200 having an alternativesealing section 202. Sidewalls 210 of the housing 200 are generallysimilar to the sidewalls 110 described above with reference to FIG. 1.The sealing section 202 includes a flange 204 that extendsperpendicularly inward from the inner section 130 of the sidewall 210 toprovide a planar seating surface 212. A filter 206 having a gasket 208disposed on top of a portion of a filter frame 214 is urged against theflange 204, thereby compressing the gasket 208 against the flange 204 toprovide a seal between the housing 200 and filter 206. It iscontemplated that the gasket 208 may be alternatively coupled to theflange 204 of the housing 200.

Returning to FIG. 1, the filter 108 is secured to the housing 106 by apawl tab 150 mounted on a standoff 152 coupled to the flange 136. Thepawl tab 150 may be rotated about a stud 154 extending from the standoff152 to provide clearance for removing/replacing the filter 108. Once thefilter 108 is inserted into the housing assembly 106, the pawl tab 150is rotated to capture the filter 108 against the flange 136 (as shown).A locking nut 156 threaded on the stud 154 secures the pawl tab 150 inposition.

The stud 154 may optionally extend to about the second end 126 of thesidewalls 110 to facilitate coupling a perforated or expanded screen 158across the open end of the housing assembly 106. The screen 158 has aplurality of mounting holes 162 configured to accept the studs 154. Anacorn nut 160 or other fastener is coupled to the stud 154 to secure thescreen 158 to the housing assembly 106.

A trim ring 164 is disposed between the screen 158 and the housingassembly 106 to cover the interface of the housing assembly 106 andceiling 102 of the cleanroom 104. Caulk, or other sealant (not shown)may be applied between the trim ring 164 and ceiling 102 to preventleakage between the cleanroom and an unfiltered area 166 above theceiling 102. In most applications, the pressure in the cleanroom 104 isgreater than the pressure in the area 166 to prevent leakage from thearea 166 into the cleanroom 104.

The trim ring 164 is generally comprised of stainless steel, aluminum orother rigid material. The trim ring 164 is comprised of a picture frame168 defining an aperture 170 and having a flange 172 extending into theaperture 170 substantially perpendicular to the picture frame 168. Inthe embodiment depicted in FIG. 1, the picture frame 168 is rectangular.The picture frame 168 is configured to extend from an inner surface ofthe inner section 130 of the sidewall 110 to cover a hole 174 in theceiling 102 in which the housing assembly 106 is mounted.

The flange 172 is disposed against the inner surface of the sidewalls110 when the trim ring 164 is mounted to the housing assembly 106. Theflange 172 includes a plurality of mounting holes 176 formed therein tofacilitate coupling the trim ring 164 to the housing assembly 106. Afastener 178, such as a rivet, self-tapping screw or other device isdisposed through the mounting hole 176 of the trim ring 164 and into thesidewall 110 to secure the trim ring 164. A mounting hole 188 for thefastener 178 is typically formed through the inner section 130 of thesidewall 110 at installation by drilling or use of a self-tapping screw.

The housing assembly 106 may include an optional diffuser plate 144coupled to the housing 180 and extending into the interior volume 114 ofthe housing assembly 106. The diffuser plate 144 is typically configuredto uniformly distribute air entering through the inlet 182 into thehousing 180, such that a uniform airflow distribution through the filter108 is realized. Generally, the diffuser plate 144 is positioned, sizedand shaped to provide uniform aerosol and airflow uniformity for apredefined housing geometry. The diffuser plate 144 may be fabricatedfrom a metal or plastic material, and may be slotted, perforated orexpanded to allow at least some air flow therethrough.

The damper assembly 122 is mounted to the housing 180 and controls theflow of air into the interior volume 114. In the embodiment depicted inFIG. 1, the damper assembly 122 is coupled to the backplate 112.Alternatively, the damper assembly 122 maybe coupled to the sidewalls110 or the collar 116. The damper assembly 122 may be closed tosubstantially stop the air flowing into the housing assembly 106 duringreplacement of the filter 108. The damper assembly 122 may also beincrementally opened to balance the air flowing into the cleanroom 104between other filters (not shown) providing air to the cleanroom 104.

FIG. 3 is a partial sectional view of the housing assembly 106illustrating the damper assembly 122. The damper assembly 122 includes aseal member 302 coupled to support member 304 by an adjustment mechanism306. A sealing element 310 is disposed between the housing assembly 106and seal member 302. The adjustment mechanism 306 is adapted to move theseal member 302 between a first position that allows air (or other gas)into the internal volume 114 of the housing assembly 106 and a secondposition that prevents flow through the inlet 182 of the housingassembly 106. Accordingly, the adjustment mechanism 306 may be utilizedto selectively control the spacing between the housing assembly 106 andthe seal member 302, thereby controlling the flow of air through theinlet 182 and ultimately through the filter 108.

The seal member 302 is fabricated from a material non-permeable to airat pressure differentials typically encountered in ventilation systems.Materials suitable for fabricating the seal member include metals, suchas aluminum or stainless steel, or other materials such as plastic, orglass reinforced plastic, among others. The seal member 302 is generallyconfigured with a plan area larger than the diameter of the inlet 182.The seal member 302 may have polygonal, disk or other plan form.

The horizontal sectional profile of the seal member 302 may vary toprovide a predetermined distribution of air flow and/or pressure withinthe internal volume 114 of the housing assembly 106. The seal member 302may have a flat, conical, dome, bowl, convex, concave, spherical orother sectional shape. In the embodiment depicted in FIG. 3, the sealmember 302 has a truncated cone shape.

The seal member 302 generally includes an outer portion 308 and a centerportion 314. The outer portion 308 supports the sealing element 310 on aside of the seal member 302 facing the inlet 182. In the embodimentdepicted in FIG. 3, a channel 312 is formed in the outer portion 308 ofthe seal member 302 to position the sealing element 310 in a predefinedposition relative to the inlet 182. For example, the channel 312 issubstantially centered relative to the lip 184 that extends into theinternal volume 114 of the housing assembly 106 so that the force perunit area of the lip 184 against the sealing element 310 ensures abubble-tight seal of the inlet 182, thereby preventing flow into thehousing assembly 106.

The sealing element 310 may be any material suitable for providing abubble-tight seal between the seal member 302 and housing assembly 106.Examples of suitable sealing elements 310 include gaskets, gels andbladders, among others. Examples of suitable gasket materials includeneoprene, foamed urethane, silicone, butyl, viton and the like. Examplesof suitable gel materials include polymeric gel, polymeric thermosetgel, polymeric thermoplastic elastomer gel, silicon gel, polyurethanegel, and the like. In the embodiment depicted in FIG. 3, the sealingelement is a polyurethane gel that allows penetration of the lip 184,thereby ensuring a bubble-tight seal.

It is contemplated that the sealing element 310 may be sealingly engagedby the housing assembly 106 and seal member 302 in other configurations.For example, the sealing element 310 may be coupled to at least one ofthe housing assembly 106 and seal member 302, and provide a bubble-tightseal without engaging a lip, as shown in FIG. 4A. In another example,the sealing element 310 may be coupled to the housing assembly 106 andengaged by a lip 402 extending from seal member 302, as shown in FIG.4B. In yet another example, the sealing element 310 may be coupled tothe housing assembly 106 within the collar 116 and engaged by a sealmember 404 configured with a diameter less than the inlet 182, as shownin FIG. 4C. In still another example, the sealing element 310 may beengaged by a lip 406 extending from seal member 404, as shown in FIG.4D. In another embodiment, the sealing member 404 may be coupled to thehousing assembly 106 within the collar 116 and of a diameter less thanthe inside diameter of the collar 116. An inflatable gasket or bladder460, coupled to at least one of the seal member 404 or collar 116, maybe inflated and urged between the inside of the collar 116 and the sealmember 404 to provide a bubble-tight seal, as shown in FIG. 4E.

The bubble-tight seal prevents air borne particles and contaminants fromentering the cleanroom. The bubble-tight seal may be tested usingpressure decay techniques, for example, as described in ASME N509-1989,Paragraph 5.9.7.3, which states that the damper seal shall be bubbletight when tested in the closed position at 10 inches water gage.Alternative seal criteria may include testing the bubble tight seal at apressure between about 3 to 15 inches water gage. It is contemplatedthat alternative seal test criteria may be utilized.

Referring back to FIG. 3, the support member 304 includes a cross bar316 and a mounting plate 318. The cross bar 316 is coupled to oppositesidewalls 110 of the housing 180. The mounting plate 318 is coupled tothe center of the cross bar 316 and provides an anchor for theadjustment mechanism 306. In the embodiment depicted in FIG. 3, both thecross bar 316 and the mounting plate 318 have a “U” shaped cross sectionto limit deflection.

Referring additionally to FIG. 5, the end of the cross bar 316 iscoupled to a tab 502 that extends into the housing 180 from the sidewall110. The opposite end of the cross bar 316 (not shown) is similarlyattached to the opposite sidewall 110. The tab 502 may be coupled to thesidewall 110 by any method that does not generate a leak path into (orout of) the housing 180. In the embodiment depicted in FIG. 5, the tab502 is welded to the housing 180. The cross bar 316 may be coupled tothe tab 502 by any suitable method, such as welding, riveting fasteningand the like. In the embodiment depicted in FIG. 5, the tab 502 iscoupled to the cross bar 316 by a fastener 504, such as a machine screwand locknut, or rivet. Alternatively, the cross bar 316 may be coupleddirectly to the sidewall 110 and/or backplate 112 by any method thatdoes not generate a leak path into (or out of) the housing 180.

The adjustment mechanism 306 is generally suitable to control thespacing between the seal member 302 and the inlet 182. Suitableadjustment mechanisms 306 include lead screws, ball screws, acme screws,linear actuators, electric motors, fluid cylinders, and mechanicallinkages among others. In one embodiment, the adjustment mechanism 306includes a lead screw 330, a drive nut 340 and a rotary cable 338. Therotary cable 338 is coupled to a shaft 332 extending from the lead screw330 opposite the drive nut 340 and is utilized to rotate the lead screw330, thereby controlling the position of the drive nut 340 along thelead screw 330.

The lead screw 330 is axially retained by and may rotate relative to thesupport member 304. In the embodiment depicted in FIG. 3, the shaft 332of the lead screw 330 is disposed through a hole 336 formed in the topof the mounting plate 318. A threaded portion 342 of the lead screw 330which engages the drive nut 340 has a larger diameter than the hole 336,thereby preventing the lead screw 330 from sliding through the hole 336of the mounting plate 318. A retaining ring 334 may be disposed on theshaft 332 to capture the lead screw 330 to the mounting plate 318,thereby allowing the shaft 330 to rotate freely within the hole 336without becoming disengaged from the support member 304.

The rotary cable 338 is coupled to the shaft 332 and is routed to thesidewall 110. As depicted in FIG. 5, the rotary cable 338 has an end 520retained proximate the sidewall 110 by a strap 522. The end 520 isadapted to mate with a driver (i.e., a screw driver, nut driver, hexdriver and the like, not shown) disposed through a port 510 formed inthe flange 136 of the housing 180 to facilitate adjustment of the sealmember 302. The port 510 is typically sealed by a plug 512 whenadjustment of the damper assembly 122 is complete. The port 510, or someother similar port, may also be utilized to inject an aerosol challengeor decontamination agents into the interior volume 114 without removalof the filter 108.

The drive nut 340 is coupled to the seal member 302 and is engaged bythe lead screw 330. The drive nut 340 is coupled to the center portion314 of the seal member 302. The drive nut 340 may be a weld nut, clinchnut, press nut or hole threaded into the seal member 302. The rotationof the seal member 302 is prevented by at least one pin 390 extendingfrom the housing assembly 106 and engaging a hole or slot 392 formed inthe seal member 302 radially outward of the sealing element 310. It iscontemplated that the seal member 302 may be restrained from rotation bya tab or other geometry configured to engage the support member 304 in amanner that prevents rotation of the disk as the lead screw 330 isrotated. It is also contemplated that the seal member 302 may berestrained from rotation by anti-rotation geometry incorporated into thedrive nut 340 and the lead screw 330. Thus, as the lead screw 330 isrotated, the restrained seal member 302 is moved between a secondposition sealing the inlet 182 (as shown in FIG. 3) and a first positionspacing the sealing member 310 from the housing assembly 106 (as shownin FIG. 6), thereby allowing flow through the inlet 182 and into theinterior volume 114 of the housing assembly 106.

To prevent leakage into the housing assembly 106 between the drive nut340 and the lead screw 330, a cover 370 is sealingly coupled to the sealmember 302 opposite the cross bar 316. The cover 370 generally preventsair from passing through the interface between adjustment mechanism 306and the seal member 302 while allowing adequate movement of the leadscrew 330.

In the embodiment depicted in FIG. 3, the cover 370 is a cylinder 372having a first end sealingly coupled to the seal member 302 and a secondend sealed by a cap 374. The cylinder 372 has a predetermined lengththat allows the lead screw 330 to extend into the cylinder 372 to adepth unimpeded by the cap 374 to allow sufficient travel of the drivenut 340 along lead screw 330 in order to provide a predefined flowthrough the gap created between the seal member 302 and the housingassembly 106.

Optionally, as shown in FIG. 7, the cylinder 372 may have a threadedinterior 702 that engages the threaded portion 342 of the lead screw330, thereby eliminating the need for a separate drive nut. In thisembodiment, a clearance hole 704 is provided for the lead screw 330 inthe center portion 314 of the seal member 302.

FIG. 8 depicts another embodiment of a filter module 820. The filtermodule 820 is substantially similar to the filter modules describedherein, except wherein a damper assembly 800 has a butterflyconfiguration. The damper assembly 800 includes a cross member 804having two vanes 802 coupled thereto. The vanes 802 are configured torotate relative to the cross member 804 between a closed position (asshown in FIG. 8) and an open position (shown in phantom in FIG. 8),thereby controlling the flow through the inlet 182 and into the internalvolume 114 of the housing assembly 106.

The outer edges of the vanes 802 make sealing contact with the sealelement 310 that is coupled to the housing 180 when the vanes 802 are inthe closed position. The inner edges of the vanes 802 adjacent the crossmember 804 are coupled to the cross member 804 by a flexible gasket 806.In one embodiment, the flexible gasket 806 may be an inflatable gasket.The flexible gasket 806 prevents air from leaking between the crossmember 804 and vanes 802, while allowing the vanes 802 to move relativeto the cross member 804. The cross member 804 is generally coupled tothe collar 116 in a manner similar to the coupling of the support member304 to the side walls 110 as described above. In another embodiment, theseal element 310 may be coupled to the vanes 802 and make sealingcontact with the housing 180 when the vanes 802 are in the closedposition.

A linkage 812 couples the vanes 802 to the adjustment mechanism 306. Thelinkage 812 includes a slider 810 and a pair of arms 808. The arms arepivotably coupled at opposite end to the slider 810 and the vanes 802. Adrive nut 340 is coupled to the slider 810, and upon rotation of thelead screw 330, causes the slider 810 to move along the lead screw 330,thereby actuating the vanes 802 between the open and closed position.

An optional diffuser plate 144 (shown in phantom) may be coupled to thesupport member 304 or housing assembly 106 to direct the air enteringthe housing assembly 106 and uniformly distribute the air entering thehousing assembly 106 through the inlet 182. In the embodiment depictedin FIG. 8, the diffuser plate 144 is a perforated disk coupled to thesupport member 804.

FIG. 9 depicts another embodiment of a filter module 920. The filtermodule 920 is substantially similar to the filter modules describedherein, except wherein a damper assembly 900 is in the form of aguillotine.

The damper assembly 900 includes a vane 902 slidably disposed in abracket 904 that is coupled to the housing 180. The bracket 904 includesa flange 906 which retains the vane 902 in a predefined spacing relativeto the housing 180. The bracket 904 includes an aperture 908 that allowsair into the internal volume 114 of the housing assembly 106 when thevane 902 is moved clear of the inlet 182.

A tab 912, coupled to the housing 180, retains a drive nut 340 of theadjustment mechanism 306. The lead screw 330 is disposed through thedrive nut 340 and coupled at one end to the vane 902 by a universalfitting 910. The fitting 910 allows the lead screw 330 to rotate withoutdecoupling from the vane 902. As the rotary cable 338 is rotated, thelead screw 330 advances through the drive nut 340, thereby positioningthe vane 902 relative to the inlet 182. It is contemplated that theadjustment mechanism may be a mechanical linkage, a linear actuator,pneumatic cylinder, gear motor, and the like.

The seal element 310 is coupled to the bottom side of the housing 180opposite the flange 906. In the embodiment depicted in FIG. 9, the sealelement 310 is an inflatable seal or bladder circumscribing the inlet182, which may be inflated to urge against the vane 902 when the vane902 is in a position closing the inlet 182, as shown in FIG. 9. It iscontemplated that the seal element 310 may be selectively urged againstthe vane 902 to create a bubble-tight seal between the vane 902 and thehousing assembly 106 by alternative methods.

FIG. 10 depicts a filter module 1000 having a damper assembly 1022suitable for providing a bubble-tight seal. The filter modules, alsoknown in this configuration as diffusers, which may be adapted tobenefit from the invention are generally available from Camfil Farr,Inc., located in Riverdale, N.J.

The filter module 1000 generally includes a frame 1002 having a filterelement 1004 permanently coupled thereto. In the embodiment depicted inFIG. 10, the filter element 1004 is bonded to the frame 1002 by apolyurethane adhesive 1012. A backplate 1006 is coupled to the frame1002. The frame 1002 has a depth sufficient to maintain the back plate1006 and filter element 1004 in a spaced-apart relationship, therebydefining a plenum 1008 within the filter module 1000. A collar 1014 iscoupled to the backplate 1006 and circumscribes an inlet 1010 formed inthe backplate 1006. The damper assembly 1022, which may be configuredsimilar to the damper assemblies described above, is coupled to at leastone of the backplate 1006, the frame 1002 or the collar 1014, and isgenerally suitable for providing a bubble-tight seal of the inlet 1010of the filter module 1000.

Alternatively, the filter module 1000 instead of the filter element1004, the filter module 1000 may include a perforated material and/oreggcrate grille and/or other materials, etc. and the module coupledthereto. Thus, the filter module 1000 may be configured as a LaminarFlow Module, Laminar Flow Element or Laminar Flow Diffuser. Installingthe bubble-tight damper 1022 in this configuration allows the siteoperator to seal the filter module 1000 prior to “fogging” an entireroom or laboratory.

Thus, a filter module is provided that includes a bubble-tight sealingdamper assembly. The housing may be configured to accept replaceable orpermanently potted filter elements. Although the embodiments depictedabove are described for use in cleanroom applications, the housing maybe utilized equally effective as a housing for ASHRAE filters, filtersof HEPA and higher efficiency, filters of sub-HEPA and low efficiency,carbon absorption products and the like. It is additionally contemplatedthat the filter housing may be utilized as an air return, wherein thefilter is positioned upstream of the damper assembly. The bubble-tightsealing of the damper assembly allows the cleanroom or work area to beadvantageously isolated by the filter module, thereby facilitatingmaintenance of the ventilation system, decontamination of the work area,and the like, to be preformed without exposing the work area tocontaminants upstream of the filter module, in the case of supplyapplications, or downstream of the filter module, in the case of exhaustapplications.

The inventive filter module having a bubble-tight damper allows facilityowners to isolate individual filters and decontaminate prior to filterremoval. This will eliminate exposure of the cleanroom to contaminatedplenum and supply ducts. For example, in the case where a supply filterneeds to be replaced, the bubble-tight damper of that particular hood orfilter module may be sealed and the hood or filter module decontaminatedwith the filter installed. After the decontamination process, the filtermay be removed. Because the plenum and filter are completely isolatedfrom the supply duct upstream of the hood or filter module, and theplenum area decontaminated prior to filter removal, the cleanroom willnot be exposed to decontaminated areas. Once the new filter isinstalled, the bubble-tight damper can be opened, and operation of thecleanroom may resume. Moreover, in situations where a facility ownerintends to “fog” a room for decontamination, the filter module with theintegral bubble-tight damper will allow the customer to very quickly andeasily seal each of the hoods to prevent the fogging agent from enteringthe air supply system, thereby eliminating the need to seal with plasticor some other material prior to decontamination.

Although various embodiments which incorporate the teachings of thepresent invention have been shown and described in detail herein, thoseskilled in the art can readily devise many other varied embodiments thatstill incorporate these teachings.

1. A filter housing assembly comprising: a housing having an openingadapted to receive a filter; an air passage formed through the housing;and a seal member coupled to the housing and moveable between a firstposition and at least a second position, the second position sealing thepassage.
 2. The filter housing assembly of claim 1 further comprising: acollar coupled to the housing and circumscribing the passage.
 3. Thefilter housing assembly of claim 2, wherein the collar is at least oneof cylindrical square or rectangular.
 4. The filter housing assembly ofclaim 1 further comprising: a lip coupled to at least one of the housingor seal member; and a seal element selectively engaging the lip toprevent flow through the passage.
 5. The filter housing assembly ofclaim 4, wherein the seal is a gel.
 6. The filter housing assembly ofclaim 5, wherein the gel is at least one of a polymer-based gel,polymeric thermoset, polymeric thermalplastic elastomer,polyurethane-based or silicon-based.
 7. The filter housing assembly ofclaim 4, wherein the lip extends from the seal member.
 8. The filterhousing assembly of claim 2, wherein the collar further comprises: a lipextending into the housing; and a seal element selectively engaging thelip to prevent flow through the passage.
 9. The filter housing assemblyof claim 5, wherein the seal member further comprises: a channel formedin an outer portion and having the member disposed therein.
 10. Thefilter housing assembly of claim 4, wherein the seal member is a gasket.11. The filter housing assembly of claim 4, wherein the lip and sealelement form a bubble-tight seal.
 12. The filter housing assembly ofclaim 1 further comprising: a collar; and a seal element engaging theseal member and collar when the seal member is in the second position.13. The filter housing assembly of claim 1, wherein the seal member isnot permeable to air across its plan area.
 14. The filter housingassembly of claim 1, wherein a sectional profile of the seal member isat least one of flat, conical, domed, spherical, convex, concave, orbowl-shaped.
 15. The filter housing assembly of claim 1 furthercomprising: a support member coupled to the housing; and an adjustmentmechanism coupled to the support bar and adapted to move the seal memberbetween the first position and at least the second position.
 16. Thefilter housing assembly of claim 15, wherein the adjustment mechanismfurther comprises: a lead screw; a nut coupled to the seal member andengaging the lead screw; and a rotary cable coupled to adapt to rotatethe lead screw.
 17. The filter housing assembly of claim 1, wherein theseal member further comprises: a butterfly damper.
 18. The filterhousing assembly of claim 1, wherein the seal member further comprises aguillotine damper.
 19. The filter housing assembly of claim 18 furthercomprising: a seal element coupled to an inflatable seal element coupledto the housing and adapted to provide a seal between the seal member ofthe guillotine damper and the housing when inflated.
 20. The filterhousing assembly of claim 1 further comprising: a diffused platedisposed proximate the passage and in a volume defined within thehousing.
 21. The filter housing assembly of claim 18, wherein the airdeflector is permeable.
 22. The filter housing assembly of claim 1further comprising: a seal element selectively providing a seal betweenthe seal member and the housing, the seal element further comprising: atleast one of a gasket, gel or an inflatable seal.
 23. The filter housingassembly of claim 1 further comprising: a filter disposed in an openingof the housing opposite the passage.
 24. The filter housing assembly ofclaim 23, wherein the filter is coupled to the housing by an adhesive.25. The filter housing assembly of claim 23, wherein the filter isreplaceable from a roomside of the housing assembly.
 26. The filterhousing assembly of claim 25, wherein the housing further comprises: aknife edge adapted to penetrate a gel disposed in the replaceablefilter.
 27. The filter housing assembly of claim 25 further comprising:a gasket sealingly disposed between the housing and the replaceablefilter.
 28. A filter housing assembly comprising: a housing having anopening adapted to receive a replaceable air filter; an passage formedthrough the housing; a seal member having an outer portion and an innerportion, wherein the outer portion is disposed closer to the opening ofthe housing than the inner portion; a seal element; a lip coupled to atleast one of the seal members and the housing; a lip circumscribing thepassage and coupled to at least one of the housing and the seal member;and a seal sealing the lip to at least one of the seal members andhousing to selectively seal the passage.
 29. The filter housing assemblyof claim 28, wherein a sectional profile of the seal member is at leastone of conical, dome, spherical, convex, concave or bowl-shaped.
 30. Thefilter housing assembly of claim 28, wherein the seal element is atleast one of a gel, gasket or inflatable seal.
 31. The filter housingassembly of claim 28, wherein the seal member is configured as part ofat least one of a guillotine damper or a butterfly damper.
 32. Thefilter housing assembly of claim 28 further comprising: a filterpermanently coupled to the opening of the housing by an adhesive. 33.The filter housing assembly of claim 28 further comprising: a filterreplaceably coupled to the opening of the housing.
 34. A method forreplacing a filter comprising: sealing an passage to a filter housingassembly retaining an air filter; removing the air filter from thefilter housing; installing a replacement filter in the filter housing;and unsealing the seal from the passage of the housing to allow air flowthrough the filter.
 35. The method of claim 34, wherein the step ofsealing further comprises: closing a damper integrally connected to thehousing assembly.
 36. The method of claim 35, wherein the damper has abutterfly damper configuration.
 37. The method of claim 35, wherein thedamper has a guillotine damper configuration.
 38. The method of claim34, wherein the step of sealing further comprises: moving a seal memberinto a position that sealingly engages a seal element with at least oneof the filter housing or a collar coupled to the filter housing to sealthe passage.
 39. The method of claim 38, wherein the step of moving theseal member further comprises: penetrating a gel with a knife edge. 40.The method of claim 38, wherein the step of moving the seal memberfurther comprises: compressing a gasket.
 41. The method of claim 34,wherein the step of sealing further comprises: inflating an inflatableseal.
 42. The method of claim 34 further comprising the step ofinjecting a decontamination agent upstream of the filter between thesteps of sealing the passage and removing the filter.